Method of manufacturing a multibore barrel



Dec. 8, 1964 J. R. EVES METHOD OF MANUFACTURING A MULTIBORE BARREL Filed Feb. 8, 1965 3 Sheets-Sheet l INVENTOR. J as E1111 R EVE5 Dec. 8, 1964 J. R. EVES 3,159,903

METHOD OF MANUFACTURING A MULTIBORE BARREL Filed Feb. 8, 1963 :5 Sheets-Sheet 2 INVENTOR JUEE h Rivas BY 'm. J M ,41% a: 3

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Dec. 8, 1964 J. R. EVES 3,159,903

METHOD OF MANUFACTURING A MULTIBORE BARREL Filed Feb. 8, 1963 3 Sheets-Sheet 3 Eigllll. (34 6) INVENTOR. JusE h R Eves 24 BY #4443 W M. ,WaMQ

United States Patent 3,159,963 METHOD 9F MANUFAQTURING A MULTEBORE BARREL Joseph R. Eves, Springfield, Mass, assignor to the Unite States of America as represented by the Secretary of the Army Filed Feb. 8, 1963, Ser. No. 257,824 2 Claims. (Ci. 29-11) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to gun barrels and pertains more particularly to the methods of manufacture thereof.

Heretofore, it has been useless trying to design a gun for firing a plurality of rounds simultaneously through a singlebarrel because there was no known, practical way, for drilling a plurality of bores in the barrel so that they would be related within tolerable limits.

It is the object of this invention to provide a method for manufacturing a barrel with a plurality of bores, whereby the bores are parallelly related to a high degree of accuracy.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

'FIG. 1 is a longitudinally cross-sectioned view of the drilled bar from which the barrel, holding fixture is fabricated;

FIG. 2 is a perspective view of the bank from which the barrel is fabricated and shows the indexing flats formed on the ends;

FIG. 3 is a longitudinally corss-sectioned view of the center locating template fitted to one end of the barrel blank with a center formed therein by a drill;

FIG. 4 is a longitudinally cross-sectioned view of the barrel blank inserted through the fixture bar and fixed thereto by welding;

FIG. 5 is a side view of the assembled barrel blank and fixture bar mounted on a lathe with the outside surface thereof being partially turned down around the centers in the barrel blank;

FIG. 6 is a longitudinally cross-sectioned view of the barrel blank indexed in the finished fixture;

FIG. 7 is a longitudinally cross-sectioned view of the fixture and barrel blank mounted in a drill machine and shows one bore drilled in the barrel blank;

FIG. 8 is an enlarged view taken along line 8-8 of FIG. 7 but showing the second bore partially drilled;

FIG. 9 is a view taken along line 9-9 of FIG. 8; and

FIG. 10 is an enlarged end view of the barrel after the three bores are drilled therein.

Illustrated in the drawings are the progressive steps whereby a barrel 12 with three bores 14 (FIG. 10) is manufactured from a cylindrical blank 16 so that the bores are parallelly related to a high degree of accuracy. The selected embodiment illustrates the custom manufacture of barrel 12 and, therefore, also included are the steps for manufacturing a fixture 18 to index blank 16 for drilling and to hold the blank when bores 14 are drilled therein because the manufacture of the fixture is correlated to the manufacture of the barrel.

Shown in FIG. 1 is a cylindrical bar 20 which has a length equivalent to the design length of barrel 12 and which is drilled to form an axial hole 22 therethrough. The diameter of hole 22 is similar to the outside diameter of blank 16, after being finish machined to the design diameter of barrel 12-, so that the blank may be received by the hole for axial and rotational displacement therein without cocking.

3,159,8fi3 Patented Dec. v8, 1 964 Preparatory to insertion into fixture 18, three flats 24 are machined on each end of blank 16 so as to be respectively normal to the plane passing from from the design center line for a respective one of the bores 14, shown as X-X in FIG. 2, through the longitudinal axis of the blank whereby flats 24 on the opposite ends of the blank are arranged in coplanar pairs. One end of blank 16 is next fitted, as shown in FIG. 3, into a template 26 having a bottomed hole 28 which has the same diameter as the outside diameter of the blank. Provided at the inner end of hole 28 is a segmental lip 36 having a chordal face 32 which has contact with one of the flats 24 on the end of blank 16 which is inserted into the hole, when such end is fully bottomed in the hole, to index the blank angularly relative to the template.

Extending rearwardly through template 26 from the bottom of hole 28 is a cylindrical aperture 34 the longitudinal axis of which lies in a plane which bisects face 32.

Aperture 34 also is located so that the longitudinal axis thereof, when extended, is coincident with the design center line X-X for one of the bores 14 in blank 16 when 1 one end of the blank is fitted into hole 28 and bottomed therein. With one end of blank 16 fitted in hole 28 and face 32 in contact with one of the flats 24, a drill 36, which has the same diameter as aperture 34 and is conically pointed, is inserted through aperture 34- to drill a conical center 38 in the respective end of the blank. Template 26 is then fitted to the opposite end of blank 16 with face 32 in contact with the one of the flats 24 which corresponds to the one contacted at the opposite end and a second center 38 is formed therein.

Blank 16 is next installed through hole 22 in bar 20 as shown in FIG. 4. Blank 16 is longer than the design length of barrel 12 and, therefore, as the length of bar 20 is similar to that of thebarrel, the ends of the blank are extendable from the bar at both ends thereof. This pro- 'vides means for fixing blank 16 to bar 20. Welding, as

cated in bar 20, the outside surface of bar 28 is now eccentrically disposed relative to the axis, noted at YY, around which the bar is rotated in lathe 40. Cutting tool 44 is used to form the outside surface of bar 20 concentrically to axis YY extending through centers 38. When the outside diameter of bar 20 is turned down to size and concentric to axis Y--Y, the bar is removed from lathe 40 and the ends of blank 16 are cut off flush with the end of bar 20 to reduce the length of the blank to the design length of barrel 12 and to free the blank from the bar for removal therefrom.

The fabrication of fixture 18 is completed by drilling and tapping a pair of holes 44 in bar 29 respectively adjacent the ends thereof so that the axis of the holes lie in the same radial plane, and by installing a set screw 46 in each of the holes. Set screw 46 is terminated at the inner end by a planar surface 48 disposed normal to the long axis thereof. Fixture 18, after fabrication, may be used for the manufacture of a plurality of barrels 12.

With fixture 18 completed, blank 16 is inserted through hole 22 in the fixture and positioned so that the set screws 46 are coutactable with corresponding flats 24 at opposite ends of the blank. When set screws 46 are tightened, the pressure applied by planer surfaces 48 against the respective flats 24 accurately indexes blank 16 angularly relative to fixture 18 and secures the blank thereto. With 3 alank firmly indexed in fixture 18, the fixture is mounted n a drill machine 50 especially adapted by drilling the )OIBS of barrels. Drill machine 50 includes a chuck 52 *or gripping the outside surface of fixture 18 and a conical :upport 54 which supports the front end of the fixture, vhereby fixture 18 with blank 16 indexed therein is roatable by the drill machine around axis Y-Y, which axis is coincident withthe design center line XX for arch of the bores 14 when the blank is successively inlexed according to the flats 24. Drill machine 50 also ncludes a drill 56' which advances along axis Y-Y to mm a bore 14, the axis of which coincides with the design :enter line X-X therefor. When the first bore 14 is :ompleted, set screws 46 are unloosened and blank 16 is nanually rotated about its longitudinal axis in hole 22 o where the next pair of the flats 24 are contactable by he set screws which are then-retightened, whereby the )lank is indexed without disturbing fixture 18 in drill machine 50 so that design center line X-X for the second we of the bores is coincident with axis Y-Y. A drill,

'od 58 having the same diameter and approximate length [S the first bore 14 is inserted thereinto to maintain the,

lynamic balance of fixture 18, with blank 16 therein, when 'otated for drilling. The second and third one of the )ores 14 are similarly drilled with another drill rod 58 nsexted into the second bore 14 when completed. As the lxes of all of the bores 14 are formed coincident with lXlS Y-Y, and as axis Y-Y is not disturbed during the ntire drilling operation, the bores are parallelly related a high degree of accuracy.

From the foregoing it is apparent that a method of main.

lfacture has been provided herein whereby a barrel may )e fabricated with a plurality of bores so that the bores Lre parallelly related to a high degree of accuracy and v-hereby the number of bores which can. be drilled is irnited only by the diameters of the barrel blank and ores.

Although a particular embodiment of the invention has teen described in detail herein, it is evident that, many 'ariations may be devised within the spirit and scope hereof and the following claims are intended to include uch variations.

I claim:

1. The method of manufacturing a gun-barrel with a alurality of bores including thesteps of mounting a barrel rlank in a cylindrical fixture so that the design center,

ines for each of the bores is rotatable into coincidental elationship with the longitudinal axis of the fixture, mounting the fixture in a drill machine so as to be roatable thereby about the longitudinal axis of the fixture did the design center line for one of the bores, rotating the fixture by the drilling machine, forming a first bore in the barrel blank by advancing a drill thereinto along the longitudinal axis of the fixture, manually rotating the barrel blank about its longitudinal axis in the fixture to where the design center line for another one of the bores is coincidental with the longitudinal axis of the fixture, similarly drilling the remaining bores in the barrel blank, and inserting a drill rod into each of the bores before the next one thereof is drilled to maintain the harmonic balance of the fixture with the blank fixed therein when rotated in the drill machine.

2. The method of manufacturing a gun barrel with a plurality of bores from a cylindrical blank having a finish-machined outside surface including the steps of forming on opposite ends of the blank a plurality of flats equal to the number of the bores with the flats on each end being respectively normal to the plane extending from the design center line for a respective one of the bores through the longitudinal axis of the blank, forming a conical center in each end of the blank at the design center line for one of the bores, inserting the blank through a cylindrical bar witha concentric hole having the same diameter as the blank, fixing the blank to the bar within the hole, turning down the outside surface of the bar on a lathe so as to be concentric to the longitudinal axis formed by the centers on opposite ends of the blank, freeing the blank from the bar, installing on opposite ends of said bar means actuatable against corresponding ones of the flats on the blank to index the design center line for the bores related to the engaged ones at the flats coincidental with the longitudinal axis of the bar and to fix the blank to the bar, mounting the bar with the blank fixed therein in a drill machine for rotation thereby around the longitudinal axis of the bar, rotating the bar by the drill machine, advancing a drill into the blank along the longitudinal axis of the bar while being rotated to form one of the bores therein, and similarly drilling the remaining bores.

References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCES Dowd et 'al.: Tool Engineering, 1st Ed., N.Y., McGraw- Hill, 1923, page 61.

RICHARD H. EANES, Jr., Primary Examiner. 

1. THE METHOD OF MANUFACTURING A GUN BARREL WITH A PLURALITY OF BORES INCLUDING THE STEPS OF MOUNTING A BARREL BLANK IN A CYLINDRICAL FIXTURE SO THAT THE DESIGN CENTER LINES FOR EACH OF THE BORES IS ROTATABLE INTO COINCIDENTAL RELATIONSHIP WITH THE LONGITUDINAL AXIS OF THE FIXTURE, MOUNTING THE FIXTURE IN A DRILL MACHINE SO AS TO BE ROTATABLE THEREBY ABOUT THE LONGITUDINAL AXIS OF THE FIXTURE AND THE DESIGN CENTER LINE FOR ONE OF THE BORES, ROTATING THE FIXTURE BY THE DRILLING MACHINE, FORMING A FIRST BORE IN THE BARREL BLANK BY ADVANCING A DRILL THEREINTO ALONG THE LONGITUDINAL AXIS OF THE FIXTURE, MANUALLY ROTATING THE BARREL BLANK ABOUT ITS LONGITUDINAL AXIS IN THE FIXTURE TO WHERE THE DESIGN CENTER LINE FOR ANOTHER ONE OF HTE BORES IS COINCIDENTAL WITH THE LONGITUDINAL AXIS OF THE FIXTURE, SIMILARLY DRILLING THE REMAINING BORES IN THE BARREL BLANK, AND INSERTING A DRILL ROD INTO EACH OF THE BORES BEFORE THE NEXT ONE THEREOF IS DRILLED TO MAINTAIN THE HARMONIC BALANCE OF THE FIXTURE WITH THE BLANK FIXED THEREIN WHEN ROTATED IN THE DRILL MACHINE.
 2. THE METHOD OF MANUFACTURING A GUN BARREL WITH A PLURALITY OF BORES FROM A CYLINDRICAL BLANK HAVING A FINISH-MACHINED OUTSIDE SURFACE INCLUDING THE STEPS OF FORMING ON OPPOSITE ENDS OF THE BLANK A PLURALITY OF FLATS EQUAL TO THE NUMBER OF THE BORES WITH THE FLATS ON EACH END BEING RESPECTIVELY NORMAL TO THE PLANE EXTENDING FROM THE DESIGN CENTER LINE FOR A RESPECTIVE ONE OF THE BORES THROUGH THE LONGITUDINAL AXIS OF THE BLANK, FORMING A CONICAL CENTER IN EACH END OF THE BLANK AT THE DESIGN CENTER LINE FOR ONE OF THE BORES, INSERTING THE BLANK THROUGH A CYLINDRICAL BAR WITH A CONCENTRIC HOLE HAVING THE SAME DIAMETER AS THE BLANK, FIXING THE BLANK TO THE BAR WITHIN THE HOLE, TURNING DOWN THE OUTSIDE SURFACE OF THE BAR ON A LATHE SO AS TO BE CONCENTRIC TO THE LONGITUDINAL AXIS FORMED BY THE CENTERS ON OPPOSITE ENDS OF THE BLANK, FREEING THE BLANK FROM THE BAR, INSTALLING ON OPPOSITE ENDS OF SAID BAR MEANS ACTUATABLE AGAINST CORRESPONDING ONES OF THE FLATS ON THE BLANK TO INDEX THE DESIGN CENTER LINE FOR THE BORES RELATED TO THE ENGAGED ONES AT THE FLATS COINCIDENTAL WITH THE LONGITUDINAL AXIS OF THE BAR AND TO FIX THE BLANK TO THE BAR, MOUNTING THE BAR WITH THE BLANK FIXED THEREIN IN A DRILL MACHINE FOR ROTATION THEREBY AROUND THE LONGITUDINAL AXIS OF THE BAR, ROTATING THE BAR BY THE DRILL MACHINE, ADVANCING A DRILL INTO THE BLANK ALONG THE LONGITUDINAL AXIS OF THE BAR WHILE BEING ROTATED TO FORM ONE OF THE BORES THEREIN, AND SIMILARLY DRILLING THE REMAINING BORES. 